驱动开发：内核监控FileObject文件回调

本篇文章与上一篇文章《驱动开发：内核注册并监控对象回调》所使用的方式是一样的都是使用ObRegisterCallbacks注册回调事件，只不过上一篇博文中LyShark将回调结构体OB_OPERATION_REGISTRATION中的ObjectType填充为了PsProcessType和PsThreadType格式从而实现监控进程与线程，本章我们需要将该结构填充为IoFileObjectType以此来实现对文件的监控，文件过滤驱动不仅仅可以用来监控文件的打开，还可以用它实现对文件的保护，一旦驱动加载则文件是不可被删除和改动的。

与进程线程回调有少许的不同，文件回调需要开启驱动的TypeInfo.SupportsObjectCallbacks开关，并定义一些微软结构，如下是我们所需要的公开结构体，可在微软官方或WinDBG中获取到最新的，将其保存为lyshark.h方便后期引用。

// 署名权
// right to sign one's name on a piece of work
// PowerBy: LyShark
// Email: me@lyshark.com
#include <ntddk.h>
#include <ntstrsafe.h>

typedef struct _CALLBACK_ENTRY
{
	LIST_ENTRY CallbackList;
	OB_OPERATION  Operations;
	ULONG Active;
	PVOID Handle;
	POBJECT_TYPE ObjectType;
	POB_PRE_OPERATION_CALLBACK  PreOperation;
	POB_POST_OPERATION_CALLBACK PostOperation;
	ULONG unknown;
} CALLBACK_ENTRY, *PCALLBACK_ENTRY;

typedef struct _LDR_DATA                         // 24 elements, 0xE0 bytes (sizeof)
{
	/*0x000*/     struct _LIST_ENTRY InLoadOrderLinks;                     // 2 elements, 0x10 bytes (sizeof)
	/*0x010*/     struct _LIST_ENTRY InMemoryOrderLinks;                   // 2 elements, 0x10 bytes (sizeof)
	/*0x020*/     struct _LIST_ENTRY InInitializationOrderLinks;           // 2 elements, 0x10 bytes (sizeof)
	/*0x030*/     VOID*        DllBase;
	/*0x038*/     VOID*        EntryPoint;
	/*0x040*/     ULONG32      SizeOfImage;
	/*0x044*/     UINT8        _PADDING0_[0x4];
	/*0x048*/     struct _UNICODE_STRING FullDllName;                      // 3 elements, 0x10 bytes (sizeof)
	/*0x058*/     struct _UNICODE_STRING BaseDllName;                      // 3 elements, 0x10 bytes (sizeof)
	/*0x068*/     ULONG32      Flags;
	/*0x06C*/     UINT16       LoadCount;
	/*0x06E*/     UINT16       TlsIndex;
	union                                                    // 2 elements, 0x10 bytes (sizeof)
	{
		/*0x070*/         struct _LIST_ENTRY HashLinks;                        // 2 elements, 0x10 bytes (sizeof)
		struct                                               // 2 elements, 0x10 bytes (sizeof)
		{
			/*0x070*/             VOID*        SectionPointer;
			/*0x078*/             ULONG32      CheckSum;
			/*0x07C*/             UINT8        _PADDING1_[0x4];
		};
	};
	union                                                    // 2 elements, 0x8 bytes (sizeof)
	{
		/*0x080*/         ULONG32      TimeDateStamp;
		/*0x080*/         VOID*        LoadedImports;
	};
	/*0x088*/     struct _ACTIVATION_CONTEXT* EntryPointActivationContext;
	/*0x090*/     VOID*        PatchInformation;
	/*0x098*/     struct _LIST_ENTRY ForwarderLinks;                       // 2 elements, 0x10 bytes (sizeof)
	/*0x0A8*/     struct _LIST_ENTRY ServiceTagLinks;                      // 2 elements, 0x10 bytes (sizeof)
	/*0x0B8*/     struct _LIST_ENTRY StaticLinks;                          // 2 elements, 0x10 bytes (sizeof)
	/*0x0C8*/     VOID*        ContextInformation;
	/*0x0D0*/     UINT64       OriginalBase;
	/*0x0D8*/     union _LARGE_INTEGER LoadTime;                           // 4 elements, 0x8 bytes (sizeof)
}LDR_DATA, *PLDR_DATA;

typedef struct _OBJECT_TYPE_INITIALIZER                                                                                                                                         // 25 elements, 0x70 bytes (sizeof)
{
	/*0x000*/     UINT16       Length;
	union                                                                                                                                                                       // 2 elements, 0x1 bytes (sizeof)
	{
		/*0x002*/         UINT8        ObjectTypeFlags;
		struct                                                                                                                                                                  // 7 elements, 0x1 bytes (sizeof)
		{
			/*0x002*/             UINT8        CaseInsensitive : 1;                                                                                                                                   // 0 BitPosition
			/*0x002*/             UINT8        UnnamedObjectsOnly : 1;                                                                                                                                // 1 BitPosition
			/*0x002*/             UINT8        UseDefaultObject : 1;                                                                                                                                  // 2 BitPosition
			/*0x002*/             UINT8        SecurityRequired : 1;                                                                                                                                  // 3 BitPosition
			/*0x002*/             UINT8        MaintainHandleCount : 1;                                                                                                                               // 4 BitPosition
			/*0x002*/             UINT8        MaintainTypeList : 1;                                                                                                                                  // 5 BitPosition
			/*0x002*/             UINT8        SupportsObjectCallbacks : 1;                                                                                                                           // 6 BitPosition
		};
	};
	/*0x004*/     ULONG32      ObjectTypeCode;
	/*0x008*/     ULONG32      InvalidAttributes;
	/*0x00C*/     struct _GENERIC_MAPPING GenericMapping;                                                                                                                                     // 4 elements, 0x10 bytes (sizeof)
	/*0x01C*/     ULONG32      ValidAccessMask;
	/*0x020*/     ULONG32      RetainAccess;
	/*0x024*/     enum _POOL_TYPE PoolType;
	/*0x028*/     ULONG32      DefaultPagedPoolCharge;
	/*0x02C*/     ULONG32      DefaultNonPagedPoolCharge;
	/*0x030*/     PVOID DumpProcedure;
	/*0x038*/     PVOID OpenProcedure;
	/*0x040*/     PVOID CloseProcedure;
	/*0x048*/     PVOID DeleteProcedure;
	/*0x050*/     PVOID ParseProcedure;
	/*0x058*/     PVOID SecurityProcedure;
	/*0x060*/     PVOID QueryNameProcedure;
	/*0x068*/     PVOID OkayToCloseProcedure;
}OBJECT_TYPE_INITIALIZER, *POBJECT_TYPE_INITIALIZER;

typedef struct _EX_PUSH_LOCK                 // 7 elements, 0x8 bytes (sizeof)
{
	union                                    // 3 elements, 0x8 bytes (sizeof)
	{
		struct                               // 5 elements, 0x8 bytes (sizeof)
		{
			/*0x000*/             UINT64       Locked : 1;         // 0 BitPosition
			/*0x000*/             UINT64       Waiting : 1;        // 1 BitPosition
			/*0x000*/             UINT64       Waking : 1;         // 2 BitPosition
			/*0x000*/             UINT64       MultipleShared : 1; // 3 BitPosition
			/*0x000*/             UINT64       Shared : 60;        // 4 BitPosition
		};
		/*0x000*/         UINT64       Value;
		/*0x000*/         VOID*        Ptr;
	};
}EX_PUSH_LOCK, *PEX_PUSH_LOCK;

typedef struct _MY_OBJECT_TYPE                   // 12 elements, 0xD0 bytes (sizeof)
{
	/*0x000*/     struct _LIST_ENTRY TypeList;              // 2 elements, 0x10 bytes (sizeof)
	/*0x010*/     struct _UNICODE_STRING Name;              // 3 elements, 0x10 bytes (sizeof)
	/*0x020*/     VOID*        DefaultObject;
	/*0x028*/     UINT8        Index;
	/*0x029*/     UINT8        _PADDING0_[0x3];
	/*0x02C*/     ULONG32      TotalNumberOfObjects;
	/*0x030*/     ULONG32      TotalNumberOfHandles;
	/*0x034*/     ULONG32      HighWaterNumberOfObjects;
	/*0x038*/     ULONG32      HighWaterNumberOfHandles;
	/*0x03C*/     UINT8        _PADDING1_[0x4];
	/*0x040*/     struct _OBJECT_TYPE_INITIALIZER TypeInfo; // 25 elements, 0x70 bytes (sizeof)
	/*0x0B0*/     struct _EX_PUSH_LOCK TypeLock;            // 7 elements, 0x8 bytes (sizeof)
	/*0x0B8*/     ULONG32      Key;
	/*0x0BC*/     UINT8        _PADDING2_[0x4];
	/*0x0C0*/     struct _LIST_ENTRY CallbackList;          // 2 elements, 0x10 bytes (sizeof)
}MY_OBJECT_TYPE, *PMY_OBJECT_TYPE;

对于开启了TypeInfo.SupportsObjectCallbacks属性的驱动来说自然就支持文件路径转换，当系统中有文件被加载则自动执行LySharkFileObjectpreCall回调事件，过滤掉无效路径后即可直接输出，完整代码如下所示；

// 署名权
// right to sign one's name on a piece of work
// PowerBy: LyShark
// Email: me@lyshark.com

#include "lyshark.h"

PVOID obHandle;
DRIVER_INITIALIZE DriverEntry;

// 文件回调
OB_PREOP_CALLBACK_STATUS LySharkFileObjectpreCall(PVOID RegistrationContext, POB_PRE_OPERATION_INFORMATION OperationInformation)
{
	UNICODE_STRING DosName;
	PFILE_OBJECT fileo = OperationInformation->Object;
	HANDLE CurrentProcessId = PsGetCurrentProcessId();
	UNREFERENCED_PARAMETER(RegistrationContext);

	if (OperationInformation->ObjectType != *IoFileObjectType)
	{
		return OB_PREOP_SUCCESS;
	}

	// 过滤无效指针
	if (fileo->FileName.Buffer == NULL ||
		!MmIsAddressValid(fileo->FileName.Buffer) ||
		fileo->DeviceObject == NULL ||
		!MmIsAddressValid(fileo->DeviceObject))
	{
		return OB_PREOP_SUCCESS;
	}

	// 过滤无效路径
	if (!_wcsicmp(fileo->FileName.Buffer, L"\\Endpoint") ||
		!_wcsicmp(fileo->FileName.Buffer, L"?") ||
		!_wcsicmp(fileo->FileName.Buffer, L"\\.\\.") ||
		!_wcsicmp(fileo->FileName.Buffer, L"\\"))
	{
		return OB_PREOP_SUCCESS;
	}

	// 将对象转为DOS路径
	RtlVolumeDeviceToDosName(fileo->DeviceObject, &DosName);
	DbgPrint("[LyShark] 进程PID = %ld | 文件路径 = %wZ%wZ \n", (ULONG64)CurrentProcessId, &DosName, &fileo->FileName);

	return OB_PREOP_SUCCESS;
}

VOID EnableObType(POBJECT_TYPE ObjectType)
{
	PMY_OBJECT_TYPE myobtype = (PMY_OBJECT_TYPE)ObjectType;
	myobtype->TypeInfo.SupportsObjectCallbacks = 1;
}

VOID UnDriver(PDRIVER_OBJECT driver)
{
	UNREFERENCED_PARAMETER(driver);
	ObUnRegisterCallbacks(obHandle);
}

NTSTATUS DriverEntry(IN PDRIVER_OBJECT Driver, PUNICODE_STRING RegistryPath)
{
	NTSTATUS status = STATUS_SUCCESS;
	PLDR_DATA ldr;

	DbgPrint("hello lyshark.com \n");

	OB_CALLBACK_REGISTRATION obRegFileCallBack;
	OB_OPERATION_REGISTRATION opRegFileCallBack;

	// enable IoFileObjectType
	EnableObType(*IoFileObjectType);

	// bypass MmVerifyCallbackFunction
	ldr = (PLDR_DATA)Driver->DriverSection;
	ldr->Flags |= 0x20;

	// 初始化回调
	memset(&obRegFileCallBack, 0, sizeof(obRegFileCallBack));
	obRegFileCallBack.Version = ObGetFilterVersion();
	obRegFileCallBack.OperationRegistrationCount = 1;
	obRegFileCallBack.RegistrationContext = NULL;
	RtlInitUnicodeString(&obRegFileCallBack.Altitude, L"321000");
	obRegFileCallBack.OperationRegistration = &opRegFileCallBack;

	memset(&opRegFileCallBack, 0, sizeof(opRegFileCallBack));
	opRegFileCallBack.ObjectType = IoFileObjectType;
	opRegFileCallBack.Operations = OB_OPERATION_HANDLE_CREATE | OB_OPERATION_HANDLE_DUPLICATE;
	opRegFileCallBack.PreOperation = (POB_PRE_OPERATION_CALLBACK)&LySharkFileObjectpreCall;

	status = ObRegisterCallbacks(&obRegFileCallBack, &obHandle);
	if (!NT_SUCCESS(status))
	{
		DbgPrint("注册回调错误 \n");
		status = STATUS_UNSUCCESSFUL;
	}

	UNREFERENCED_PARAMETER(RegistryPath);
	Driver->DriverUnload = &UnDriver;
	return status;
}

运行这个驱动程序，当系统中有新文件被加载时则自动输出该文件所属进程PID以及该文件的详细路径。

至于如何阻止打开一个文件其实与《驱动开发：内核注册并监控对象回调》文章中使用的方法是一致的，首先判断OperationInformation->Operation是不是OB_OPERATION_HANDLE_CREATE或OB_OPERATION_HANDLE_DUPLICATE如果是，则直接设置Parameters->CreateHandleInformation.DesiredAccess为0直接拒绝加载。

// 文件回调
OB_PREOP_CALLBACK_STATUS LySharkFileObjectpreCall(PVOID RegistrationContext, POB_PRE_OPERATION_INFORMATION OperationInformation)
{
	UNICODE_STRING DosName;
	PFILE_OBJECT fileo = OperationInformation->Object;
	HANDLE CurrentProcessId = PsGetCurrentProcessId();
	UNREFERENCED_PARAMETER(RegistrationContext);

	if (OperationInformation->ObjectType != *IoFileObjectType)
	{
		return OB_PREOP_SUCCESS;
	}

	// 过滤无效指针
	if (fileo->FileName.Buffer == NULL ||
		!MmIsAddressValid(fileo->FileName.Buffer) ||
		fileo->DeviceObject == NULL ||
		!MmIsAddressValid(fileo->DeviceObject))
	{
		return OB_PREOP_SUCCESS;
	}

	// 过滤无效路径
	if (!_wcsicmp(fileo->FileName.Buffer, L"\\Endpoint") ||
		!_wcsicmp(fileo->FileName.Buffer, L"?") ||
		!_wcsicmp(fileo->FileName.Buffer, L"\\.\\.") ||
		!_wcsicmp(fileo->FileName.Buffer, L"\\"))
	{
		return OB_PREOP_SUCCESS;
	}

	// 阻止打开lyshark_com.txt文本
	if (wcsstr(_wcslwr(fileo->FileName.Buffer), L"lyshark_com.txt"))
	{
		if (OperationInformation->Operation == OB_OPERATION_HANDLE_CREATE)
		{
			OperationInformation->Parameters->CreateHandleInformation.DesiredAccess = 0;
		}
		if (OperationInformation->Operation == OB_OPERATION_HANDLE_DUPLICATE)
		{
			OperationInformation->Parameters->DuplicateHandleInformation.DesiredAccess = 0;
		}
		DbgPrint("[LyShark] 已拦截 lyshark_com 文件打开 \n");
	}

	return OB_PREOP_SUCCESS;
}

运行修改后的驱动程序，然后尝试打开lyshark_com.txt则会提示系统找不到指定文件。